1. Field of the Invention
This invention relates to thermally activated substrates.
More particularly, the invention relates to a thermally activated substrate which prolongs the life of thermally activated images formed on the substrate by a heated imprinting head and which prolongs the operational life of the imprinting head.
In another respect, the invention relates to a thermally activated substrate that reduces by about 25% the cost of providing a heat resistant, solvent resistant, sun resistant substrate on which alphanumeric characters or other images are formed by heated imprinting heads.
2. Description of the Related Art including Information Disclosed Under 37 CFR 1.97 and 1.98.
Thermally activated substrates, while well known in the art, produce images which have limited clarity, which fade with time, and which are susceptible to being damaged by heat, solvents, soaps, alcohols, sun screen compositions, and/or other chemical components. For example, direct thermal paper has long been utilized in facsimile machines. Documents produced by facsimile machines using direct thermal paper fade with time and are susceptible to damage by sunlight, solvents and other chemicals. Facsimile documents are fragile. Processes for protecting a facsimile document are impractical or expensive. In particular, applying a conventional 0.001 inch thick sheet of plastic to facsimile paper has long been dismissed out-of-hand because of the expense involved, because the plastic melts or becomes tacky and sticks to the thermal imprinting head, or because the plastic functions as a heat insulator which prevents the thermally sensitive coating on the fax paper from being properly activated by heat from the thermal printing head.
Another well known wax thermal transfer product is significantly more resistant to extraneous elements than the facsimile documents discussed above. During use of the wax thermal transfer product, wax is thermally transferred from a ribbon to paper, in a manner similar to that in which carbon from carbon paper interleaved between an original form sheet and a form copy positioned directly beneath the original form sheet is transferred by pressure from the carbon paper to the form copy when information is typed on the original form sheet. The pressure generated when a type head strikes the original form sheet causes carbon from the carbon paper to adhere to the form copy. Similarly, during use of the wax thermal transfer product, a heated imprinting head strikes the ribbon and presses it against a substrate. Pressure and heat generated by the imprinting head cause the wax to adhere to the substrate. While the resulting wax image is more durable than a comparable thermal image formed on facsimile paper, the wax image is not necessarily any sharper than the facsimile paper image. In addition, the wax thermal transfer product is relatively expensive and cumbersome. Once wax has been transferred from a ribbon to a piece of paper or other substrate, the ribbon must be destroyed because the information produced on the piece of paper is readily deduced simply by reading the ribbon.
Accordingly, it would be highly desirable to provide an improved process and apparatus for providing thermally activated imprinted substrates which produce images that are clearer, are resistant to solvents and heat and other extraneous elements, and are appreciably less expensive to produce than images produced with conventional thermal wax imprinting ribbons.
Therefore, it is a principal object of the invention to provide an improved apparatus and process for producing thermally activated images which appear clear, which are resistant to heat, sunlight, solvents, alcohols and other extraneous components, and which are less expensive and/or more durable than images produced with conventional wax ribbon or facsimile paper thermal processes.
Another object of the invention is to reduce the cost of producing durable thermal imprinted alphanumeric images or other imprinted images on a substrate.